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W. C. LEFEBVRE.

PROTRACTOR.

APPLICATION FILED OCT. 22, 1914. RENEWED JAN. 12,1916.

1 1 9 3,80 1 Patented Aug. 8, 1916.

2 SHEETS-SHEET 1- Elvwmdoz W. CQLEFEBVRE.

PROTRACTOR.

APPLICATION FILED OCT. 22. 1914. RENEWED JAN. 12,1916.

2 SHEETSSHEET 2- mr NORRIS PETERS cn.,Pnarn-1.nm.. wsrmw run. a, c.

WILLIAM CLAYTON LEFEBVRE, OF TUCSON, ARIZONA.

PROTRACTOR.

Application filed October 22, 1914, Serial No. 868,053. Renewed January 12, 1916. Serial No.

To all whom it may concern:

sired angle, measure the desired distance,

and draw the connecting line.

Another ob ect of the invention is to pro vlde the protractor with removable scales so that the same may be used on difierent sizes of drawings.

A further object of the invention is to pro vide a stationary member and a movable member connected for rotation so as to minimize the number of movements of the entire device.

A still further object is to provide a novel means for the connection of the members for rotation.

WVith these and other objects in view,'the

- invention consists in the novel features of construction, combination and arrangement of parts as will be hereinafter more fully described, illustrated in the accompanying drawings, and claimed.

In the drawings: Figure 1 is a plan view of the improved protractor; Fig. 2 is an enlarged similar view of the revoluble disk; Fig. 8 is a section on the line 33 of Fig. 1; Fig. 4 is a bottom plan view of the guide member; Fig. is a detail view of the sight plate; Fig. 6 is a detail view of the handle; and Fig. 7 is a detail sectional view showing the connection between the removable scales and the disk.

To lay off a given angle, from a given point on a straight line with an ordinary protractor, it is first necessary to position the base of the protractor on the given line in parallel relation thereto with the center point of the protractor coinciding with the given point, a point is then marked on the paper against the division on the periphery of the protractor coinciding with the angle desired, the protractor removed, and a line drawn through the given point and the mark.

The present invention aims to accomplish Specification of Letters Patent.

Patented Aug. 8, 1916. 71,806. I

the object of the ordinary protractor with a single operation, thus saving time and labor.

In order to accomplish the objects above set forth, a disk 1 is provided which has marked on its upper face adjacent the edges thereof the divisions 2. It is wished to be stated here that as many subdivisions may be marked on the disk between the main divisions 2, as desired. A slot 3 is cut from one side of the disk and extends a slight distance past the center thereof. This slot is provided for the reception of a scale 4, which has one edge thereof dovetailed to fit a similarly shaped dovetailed slot formed in one side of the wall of the slot 3, the scale being held in engagement with the disk by means of a leaf spring 5, seated in a recess formed adjacent the edge of the slot and adapted to normally exert a resisting pressure against the scale. The disk 1 has formed on its peripheral edge a tongue 6 and this tongue is adapted to engage a groove 7 formed in a rest plate 8 which is secured to the lower portion of a guide or supporting member 9.

In order to hold the disk 1 in engagement with the plate 8 for rotation therewith, the upper edge of the disk has secured thereto a pair of substantially semicircularly-shaped groove members 10, so that when the same are positioned as shown in Fig. 2 of the drawings they will form a guide for a plate 11, which is secured to the underside of the guide 9, and which has a tongue adapted to engage with the grooves of the plates 10, the plates 10 being formed of semicircular shape in order to facilitate the assembling of the parts of the protractor. It will be seen that when the parts above referred to are in their assembled relation, as shown in Fig. 1 of the drawing, the disk 1 will be rotatably connected with the guide or support 9.

One end of the plate 8 has a portion thereof cut away in order to accommodate the scale 4: when the disk 1 is rotated a full half turn, and in order to provide a sight to tell when the protractor is parallel with the line on which it is being used, a plate 12 is connected to the plate 8 and has its outer edge flush with the straight edge of the support 9. A handle 13 is provided for the rotation of the disk 1, the guide member 9 having a slot 14 formed therein to accommodate the shank of the handle when the disk is moved a full half revolution.

By reference to the drawings it will be seen that the scale 4 is of a width slightly less than the slot 3, so that a space 15 is provided between the working edge of the scale and the adjacent wall of the disk to provide for plotting from the center of the disk to the outer edge thereof. A V-shaped recess 16 is cut in the straight wall of the guide member 9 to enable the user of the protractor to clearly see the center point from which he is working. By again referring to the drawings it will be seen that the disk 1 has two sides thereof marked'with degrees from 0 to 180, so that when the disk is turned in the guide 9, the straight edge of the guide may be used for ascertaining the degree desired. It will also be seen from the construction above set forth that by turning the disk 1 in the guide 9, the desired angle may be obtained and the distance marked on a straight edge with a sin gle operation.

From the foregoing description taken in connection with the accompanying drawings it is thought that the construction and operation of the device will be clearly understood, and while I have herein shown and described one specific form of my invention, I do not wish to be limited thereto except for such limitation as the claims may im port.

I claim 1. A protractor comprising a disk, a guide for said disk, said guide having a rest plate formed on one face thereof, said plate being provided with a groove, a tongue formed on said disk for engagement with said groove, and a handle for rotating-said disk.

2. A protractor comprising a disk, a guide for said disk, said guide provided with a slot and having a rest plate formed on one face thereof, said plate being provided with a groove, a tongue formed on said disk for engagement with said groove, a plate fastenedto said disk, a plate fastened to said guide for engagement with the last mentioned plate, and a handle adapted to extend into said slot when the disk is revolved.

3. A protractor comprising a disk, a guide for said disk, said guide having a rest plate formed on its under face, said plate being provided with a groove, a tongue formed on said disk for engagement with said groove,'a plate provided with a groove and fastened to said disk, a plate fastened to said guide, a tongue formed on said last named plate for engagement wit-h the groove of the first mentioned plate, and a scale removably mounted on said disk.

4k A protractor comprising a disk, a guide fOr said disk, said guide having a rest plate formed on its under face, said plate being provided with a groove a tongue formed said disk for engagement with said groove,

a plate provided with a groove and fastened to said disk, a plate fastened to said guide,

a tongue formed on said last named plate for engagement with the groove of the plate fastened to the disk, a scale removably mounted on said disk, and a spring clip to hold said scale in engagement with the disk.

6. A protractor comprising a disk, a guide for said disk, said guide having a rest plate formed on its under face, said plate being provided with a groove said rest plate formed adjacent the periphery of the guide and terminating short of the straight edge thereof, a tongue formed on said disk for engagement with said groove, a plate provided with a groove and fastened to said disk, a plate fastened to said guide, a tongue formed on said last named plate for engagement with the groove of the plate fastened to the disk, a scale removably mounted on said disk, and a plate fastened to the rest plate to facilitate the positioning of the guide.

In testimony whereof I aflix my signature in presence of two witnesses.

WILLIAM CLAYTON LEFEBVRE. Witnesses:

JAMES V. CLYNE, CHAS. E. WOODELL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, I). G. 

